There are some sites that have scraped the average movie ratings at various sites such as IMDB, Rotten Tomatos and Allmovies. Here is one particularly good (and still online) job.
Still, this is all aggregate data. Perhaps we are more interesting in how people rate movies. One does have the option to make one’s profile public. One can use advanced google search to find these public profiles, of which I found about 140k.
The users generally do not provide much personal information (e.g. this user page, or my own), so one would be unable to correlate this with their preferences. Still, one can compare their ratings on different movies and find clusters of movie watchers. It would probably be an interesting project for a computer science student, or just someone who likes to do data science for fun (like me).